video: add lm3533 backlight driver

This is basic lm3533 driver only with bank A and backlight cell
support.

Tested-by: Andreas Westman Dorcsak <hedmoo@yahoo.com> # LG P880 T30
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # LG P895 T30
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/video/Kconfig

@@ -606,6 +606,15 @@ config ATMEL_HLCD
 	help
 	   HLCDC supports video output to an attached LCD panel.
 
+config BACKLIGHT_LM3533
+	bool "Backlight Driver for LM3533"
+	depends on BACKLIGHT
+	select DM_I2C
+	help
+	  Say Y to enable the backlight driver for National Semiconductor / TI
+	  LM3533 Lighting Power chip. Only Bank A is supported as for now.
+	  Supported backlight level range is from 2 to 255 with step of 1.
+
 source "drivers/video/ti/Kconfig"
 
 source "drivers/video/exynos/Kconfig"

drivers/video/Makefile

@@ -28,6 +28,7 @@ obj-$(CONFIG_VIDEO_LOGO) += u_boot_logo.o
 
 endif
 
+obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_backlight.o
 obj-${CONFIG_EXYNOS_FB} += exynos/
 obj-${CONFIG_VIDEO_ROCKCHIP} += rockchip/
 obj-${CONFIG_VIDEO_STM32} += stm32/

drivers/video/lm3533_backlight.c

@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2022 Svyatoslav Ryhel <clamor95@gmail.com>
+ */
+
+#define LOG_CATEGORY UCLASS_PANEL_BACKLIGHT
+
+#include <backlight.h>
+#include <common.h>
+#include <dm.h>
+#include <i2c.h>
+#include <log.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <asm/gpio.h>
+
+#define LM3533_BL_MIN_BRIGHTNESS			0x02
+#define LM3533_BL_MAX_BRIGHTNESS			0xFF
+
+#define LM3533_SINK_OUTPUT_CONFIG_1			0x10
+#define LM3533_CONTROL_BANK_A_PWM			0x14
+#define LM3533_CONTROL_BANK_AB_BRIGHTNESS		0x1A
+#define LM3533_CONTROL_BANK_A_FULLSCALE_CURRENT		0x1F
+#define LM3533_CONTROL_BANK_ENABLE			0x27
+#define LM3533_OVP_FREQUENCY_PWM_POLARITY		0x2C
+#define LM3533_BRIGHTNESS_REGISTER_A			0x40
+
+struct lm3533_backlight_priv {
+	struct gpio_desc enable_gpio;
+	u32 def_bl_lvl;
+};
+
+static int lm3533_backlight_enable(struct udevice *dev)
+{
+	struct lm3533_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	dm_gpio_set_value(&priv->enable_gpio, 1);
+	mdelay(5);
+
+	/* HVLED 1 & 2 are controlled by Bank A */
+	ret = dm_i2c_reg_write(dev, LM3533_SINK_OUTPUT_CONFIG_1, 0x00);
+	if (ret)
+		return ret;
+
+	/* PWM input is disabled for CABC */
+	ret = dm_i2c_reg_write(dev, LM3533_CONTROL_BANK_A_PWM, 0x00);
+	if (ret)
+		return ret;
+
+	/* Linear & Control Bank A is configured for register Current control */
+	ret = dm_i2c_reg_write(dev, LM3533_CONTROL_BANK_AB_BRIGHTNESS, 0x02);
+	if (ret)
+		return ret;
+
+	/* Full-Scale Current (20.2mA) */
+	ret = dm_i2c_reg_write(dev, LM3533_CONTROL_BANK_A_FULLSCALE_CURRENT, 0x13);
+	if (ret)
+		return ret;
+
+	/* Control Bank A is enable */
+	ret = dm_i2c_reg_write(dev, LM3533_CONTROL_BANK_ENABLE, 0x01);
+	if (ret)
+		return ret;
+
+	ret = dm_i2c_reg_write(dev, LM3533_OVP_FREQUENCY_PWM_POLARITY, 0x0A);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int lm3533_backlight_set_brightness(struct udevice *dev, int percent)
+{
+	struct lm3533_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	if (percent == BACKLIGHT_DEFAULT)
+		percent = priv->def_bl_lvl;
+
+	if (percent < LM3533_BL_MIN_BRIGHTNESS)
+		percent = LM3533_BL_MIN_BRIGHTNESS;
+
+	if (percent > LM3533_BL_MAX_BRIGHTNESS)
+		percent = LM3533_BL_MAX_BRIGHTNESS;
+
+	/* Set brightness level */
+	ret = dm_i2c_reg_write(dev, LM3533_BRIGHTNESS_REGISTER_A,
+			       percent);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int lm3533_backlight_probe(struct udevice *dev)
+{
+	struct lm3533_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	if (device_get_uclass_id(dev->parent) != UCLASS_I2C)
+		return -EPROTONOSUPPORT;
+
+	ret = gpio_request_by_name(dev, "enable-gpios", 0,
+				   &priv->enable_gpio, GPIOD_IS_OUT);
+	if (ret) {
+		log_err("Could not decode enable-gpios (%d)\n", ret);
+		return ret;
+	}
+
+	priv->def_bl_lvl = dev_read_u32_default(dev, "default-brightness-level",
+						LM3533_BL_MAX_BRIGHTNESS);
+
+	return 0;
+}
+
+static const struct backlight_ops lm3533_backlight_ops = {
+	.enable = lm3533_backlight_enable,
+	.set_brightness = lm3533_backlight_set_brightness,
+};
+
+static const struct udevice_id lm3533_backlight_ids[] = {
+	{ .compatible = "ti,lm3533" },
+	{ }
+};
+
+U_BOOT_DRIVER(lm3533_backlight) = {
+	.name		= "lm3533_backlight",
+	.id		= UCLASS_PANEL_BACKLIGHT,
+	.of_match	= lm3533_backlight_ids,
+	.probe		= lm3533_backlight_probe,
+	.ops		= &lm3533_backlight_ops,
+	.priv_auto	= sizeof(struct lm3533_backlight_priv),
+};